Evaluation of Multiaxial Low Cycle Creep-fatigue Life for Mod.9Cr-1Mo Steel under Non-proportional Loading

This study discusses the creep-fatigue strength for Mod.9Cr-1Mo steel at a high temperature of 823 K under multiaxial loading. Low cycle fatigue tests in various strain waveforms were performed with hollow cylindrical specimen. The conducted proportional loading fixed axial and non-proportional 90-degree phase difference between shear strains. different rates holding times also to discuss effects stress relaxation on failure life. In this study, two types life evaluation methods proposed: first method is calculate range using Manson’s universal slope considering factor creep damage; second damage by linear law from improved ductility exhaustion law. accuracy much better than that used actual machines such as time fraction rule. proposed authors showed highest accuracy. equation slightly less accurate second, but it useful procedure easy.